This invention relates generally to topical compositions and methods for the treatment of disorders of the skin and mucosal membranes. More specifically, the invention relates to compositions and methods for the treatment of anorectal disorders.
Anorectal disorders include hemorrhoids, fissures, ulcers, spasms and the like. Such disorders are quite common, and can adversely affect a patient""s quality of life. In some instances, such conditions can be severe enough to be incapacitating. A variety of materials and therapies have been implemented in an attempt to treat or control anorectal disorders. In those cases where the disorders are very severe, surgery may be required; however, in many instances, such conditions can be treated, with some success, by topical preparations.
Only recently has the role of nitric oxide (NO) as a mediator of smooth muscle contraction come to be understood. In view thereof, various materials such as organic nitrates and the like have been proposed for the treatment of anorectal disorders; however, such materials have been found to be difficult to formulate; and in many instances, such materials can produce adverse side effects on a patient. L arginine has been shown to act, in vivo, to enhance or contribute to the effect of NO on smooth muscle tissue, and it is speculated that such action is a result of L arginine acting as a competitive inhibitor of compounds that block the action of NO production in vivo. Therapeutic materials based upon L arginine have been employed for the treatment of hemorrhoids and the like. In this regard, see U.S. Pat. No. 5,595,753 and U.S. Pat. No. 5,827,889. However, the effect of L arginine on smooth muscle tissue has been found to be of relatively short duration. Consequently, L arginine treatments must be repeated on a frequent basis and/or relatively large volumes of material must be applied to a patient. This requirement limits the utility of such therapies.
As will be explained in detail hereinbelow, the present invention provides an L arginine based composition for the treatment of anorectal conditions, as well as other conditions associated with skin and/or mucosal membranes, which composition has a relatively long duration of action. The compositions of the present invention are simple to prepare and use, stable on storage, and have been found to provide long lasting relief from pain and discomfort associated with anorectal disorders and the like.
There is disclosed herein a topical composition which comprises, on a weight basis, 0.1-18% of L arginine and 1-15% of lidocaine. These materials are disposed in a pharmaceutically acceptable carrier. In some embodiments, the carrier includes liposomes, and in some instances the lidocaine is contained within a non-aqueous phase disposed within the liposomes. In specific embodiments, the lidocaine comprises 1-10% of the composition, and in a specifically preferred formulation, the lidocaine comprises 5% of the formulation. In some embodiments, the L arginine is typically present in an amount of 0.1-5 weight percent of the composition; in certain embodiments, it comprises 0.1-3 weight percent of the composition; and in a specifically preferred formulation, it comprises 1% of the composition. The L arginine may be present as a free base or as a salt. The composition may further include an anti-inflammatory material such as a topical corticosteroid such as hydrocortisone or a derivative thereof.
Also disclosed herein is a method for the treatment of an anorectal disorder in a patient, and the method comprises applying the topical composition of the present invention to the affected area of the patient.